Many RF power amplifier applications require high voltage, high power, wide bandwidth operation. The high breakdown voltage and current density of group III-nitride (N) (e.g. gallium nitride (GaN)) transistor technology enables such high voltage, high power, wide bandwidth operation. Such applications require stable, high gain operation at microwave frequencies. However, stability is often traded off in GaN or other power amplifier designs that provide high gain. Accordingly, there is a need for stable, high gain amplifier and integrated circuit structures amenable to GaN or other RF transistor technologies.